My guess is it's an IH gas engine...maybe a 345 or 392? The ad says it's an IH engine, but didn't give any details.Who is the manufacture/engine are parts available.
that thing's literally as aerodynamic as a brick 
Warden thats the truth its a 50mph rig 
I don't want to think about how that would handle on the highway...a slight gust would probably put it on its sidethat thing's literally as aerodynamic as a brick